The focus of this project is to investigate at the molecular level the structural basis of meiotic chromosome metabolism and segregation in the yeast, Saccharomyces cerevisiae, and to compare it to that of the mouse and related mammalian species. Methods of isolation and identification by light and electron microscopy are being developed for meiosis specific structures in yeast based on surface spreading techniques combined with immunofluorescence. Whole-mount preparations have been used to demonstrate well-preserved synaptonemal complexes in preparations of yeast meiotic nuclei, as visualized both by light and electron microscopy. Additionally, these methods combined with anti-tubulin antibody staining have allowed the stages of chromosome movement along the meiotic spindle to be elucidated. Two monoclonal antibodies against the mouse synaptonemal complex, isolated by Dresser and Moses, appear in preliminary experiments to recognize a comparable structure in yeast meiotic nuclei. The specific antigens recognized by these antibodies in yeast preparations are being determined by SDS PAGE and subsequent Western blotting. A combined cytogenetic and immunochemical analysis is being used to identify protein components of the synaptonemal complex and to determine their spatial distribution and organization.